Iwan

Hi,

I got my iMac (20" 1.8GHz G5) delivered this morning so have been busy fiddling/configuring/upgrading it all day. However, i've run into a problem installing my new memory which i got from Crucial about a week ago.

It's got 2 memory slots, i'll call them left (L) and right (R) as you look into the back of the iMac with the top furthest away from you.

The memory is 2 * 1Gb DDR400/PC3200 modules of the right flavour for the iMac G5 20".

With one in the (L) slot ONLY, it is detected correctly as a 1Gb module.

With one in the (R) slot ONLY, it is detected incorrectly as a 512Mb module.

With one in the (L) and one in the (R) slots they both detect as 512Mb each, the iMac boots up and runs fine with no errors.

With a 1Gb in the (L) and a 256Mb (which came with the iMac from Apple) in the (R), they both detect correctly and the total is 1.25Gb.

I called Crucial and they were as confused as me. I thought it might be a fault with the iMac at first but the 256Mb Apple module detects correctly in either slot. I can't understand why a 1Gb detects correctly in the (L) slot, but then decreases to 512Mb when you add another 1Gb to the (R) slot, with both slots detectign as 512Mb each.

The woman at Crucial suggested I call them back on monday and speak to their resident expert. In the meantime, has anyone here seen this before or have any ideas?

Is there some setting I need to change somewhere? I can't see any jumpers and am not even sure if the iMac has a BIOS like a PC (1st time i've used one!).



Any help greatly appreciated!

EDIT: My broadband is down at home so i'll be popping in to work periodically over the weekend to check this thread.

angrynorth

The only thing I can think is that the RAM may be bad. The G5 processors are incredibly sensitive to RAM and if you are unfortunate enough to have one stick which is slighty iffy then it may mess with the config. I am guessing Crucial will just ask you to return the sticks on Monday. Sorry

class_A

Could be that your (R) slot is screwed. Have you tried booting from the Hardware Test CD? Macs do have a kind of BIOS, it's called OpenFirmware, but you don't need to do anything in there.

Tried the usual Mac fixes of PRAM reset, PMU reset? Where are you getting your installed memory from, Apple -> About This Mac or /Applications/Utilties/System Profiler?

Have you checked the labels on the RAM sticks themselves to confirm the capacity and that they are within spec?

Iwan

Cheers for the replies guys. Yes i've checked the RAM is the correct type and is actually what I ordered. Both sticks detect as 1Gb in the (L) socket bu tnot in the (R). The Apple RAM that came with it detects ok as 256Mb in both sockets.

Haven't tried the PRAM or PMU resets yet but it's next on the list, when i can find out which key is the 'command' key.

Am finding that 20 years playing with PC's isn't much help!

Will also try booting from the hardware test CD, fortunately there was one in the box with the iMac...

At least the broadband is back up now, at a speedy 2Mb/s too!

Iwan

Curently running the extended diagnostics test, it thinks there's a fault on one of the modules so i've told it to thoroughly check all of the RAM.

Fingers crossed but it might just be a dodgy module, and nothing wrong with the iMac.

class_A

Cmd key is the Apple key or "cloverleaf" key (all the same thing). Hopefully it's just dodgy RAM, a lot less hassle to swap out and Crucial customer services are excellent if you have a problem.

rich101

Sorry to hear of your problems with the Crucial memory . .

I always run the Hardware Diag CD on anything Apple when changing memory modules. As someone mentioned before they are very sensistive to iffy memory modules. It is for the best though as a WinTel box would probably just let it go with lots of unexplained hangs and lockups later on

We have a iBook and bought a 512Mb SODIMM from an eBay Apple memory specialist, the first and second module did not work. Eventually I bought from Apple as I could not be asked to **** around any longer.

Later on we bought some 512Mb modules for an eMac and like you one module was faulty and so was the replacement ! Finally the third one was OK

I would love to buy from Apple but they really take the pi$$ with memory

Just my thoughts, enjoy your new toy, and here are a few things to look up

MactheRipper
VLC

Oh and if you have not found it this is really useful site

http://www.macosxhints.com/

If you have the time get along to the Mac Show in November, if you pre-reg around Sept, tickets are free.

We have never looked back, as everything just works when you want it too !

rich

Iwan

Cheers guys

It's looking like the iMac doesn't like either of the modules, though I've got it to recognise one of them in the (L) slot at the correct size without reporting errors during the diagnostic tests. The Apple RAM (256Mb) seems to pass the tests whichever slot it's in.

So even though it's 'working', i think i'm going to have to return both of the 1Gb modules to Crucial. What's the recommendation, should i get them changed for fresh ones or try for a refund and look elsewhere?

Not sure if I can afford Mac prices but then again, if it works.....

Got Mactheripper and VLC installed already, though I've not tried using Mactheripper yet.

I used to use VLC on the PC, top bit of software.

angrynorth

I have never had any problems with Crucial RAM, its probably just that you got unlucky. I would return it and see how the replacements are. I am guessing they will be fine. I would try ti stay away from Apples own as it is very expensive, Kingston RAM is also pretty good I suppose you could try those if you get no luck with Crucial.

Good luck

You simply HAVE to install Quicksilver too the best piece of Mac software there is.

Iwan

Just spoken to Crucial again who were extremely helpful. They're going to send me 2 replacement 1Gb modules, but they're going to send ones fitted with Micron chips instead of Samsung chips like the first lot.

Both types _should_ be compatible, but it sounds like my particular iMac doesn't like the Samsung ones.

Fingers crossed, and a to Crucial...